Tom Holland has hinted he personally proposed a major, still-secret story idea for Spider-Man: Brand New Day, fuelling speculation that he may be responsible for Sadie Sink's mystery character turning out to be Jean Grey. Holland, who has played Peter Parker for a decade and reportedly gained more creative influence on this instalment after working with Christopher Nolan and signing a stronger contract, told Polygon the idea remains "the biggest mystery" of the film and that he cannot reveal it, having pitched it to the writers' room after brainstorming with his brother and a friend.

Speculation centres on Sink, whose character's identity has been kept deliberately secret, with many assuming she is playing the X-Men's psychic mutant Jean Grey; early footage reportedly hints at a psychically powered villain at the story's core, though nothing was confirmed. Sink herself said she was not given a script until arriving to film in London, despite knowing the role she was auditioning for, and praised Holland's deep investment in getting the character and story right for fans. Spider-Man: Brand New Day is due for release in cinemas on 31 July.